Outcome of stenosis of the internal carotid artery after contralateral endarterectomy.

OBJECTIVES: The aim of the study was to evaluate clinical outcome and patterns of disease progression relating to stenosis of the internal carotid artery (ICA) opposite to the operated side, using ultrasonographic risk score of ICA plaques. METHODS: 150 patients who underwent ICA endarterectomy for transient ischemic attack (TIA) between January 1997 and December 2000 were studied prospectively. The progress (modified Strandness criteria) and ultrasonographic morphology of ICA plaques on the contralateral side were followed using digitally assisted plaque analysis. Parameters of the plaque image were analyzed and compared with neurologic events. RESULTS: Progression of contralateral stenosis from < 50% to 50-79% occurred in 11/105 patients (10.5%), all asymptomatic; from 50-79% to 80-99% in 10/31 patients (9.5%, one TIA). One patient progressed from the > 50% group to the 80-99% group and remained asymptomatic. After the progression of stenosis there were 32 patients with 50-79% stenosis and 25 with 80-99%. Among those with 50-79% stenosis, two patients developed symptoms (one TIA and one stroke). Among those with 80-99% stenosis, three patients developed symptoms (two TIAs and one stroke). Of the 105 patients who began with an initial contralateral stenosis of <50%, there remained 93; Seven developed symptoms appropriate to the contralateral carotid artery (four TIAs and three strokes). Life-table comparison (Cox's F test) of patients with < 50% stenosis (N = 93) and those with > 50% stenosis (N = 57, groups with > 50% stenosis taken together) showed no important statistical connection (F =1.71, p = 0.378). All plaques were heterogenous and there was no difference in global echogenicity. However, the activity index (AI) in patients with more than 50% stenosis (N=57, groups 50-79% and 80-99% together) was higher than 60 in 19 patients and lower than 60 in 38 patients. There were four neurologic events (three TIAs, one stroke) in the first group (AI > 60) and one neurologic event in the second (one stroke). Life-table comparison (Cox's F test) of the two groups based on the AI showed a significant difference (F=8.84, p=0.001). 18 patients were operated on the contralateral side on the basis of an elevated ultrasonographic AI. There was no morbidity or mortality in the operated group. CONCLUSIONS: Digitally assisted analysis of ultrasonographic ICA plaque morphology is unable to identify high-risk plaques in patients with less than 50% stenosis. In asymptomatic patients with more than 50% stenosis, an ultrasonographic plaque AI higher than 60 may contribute to a more objective selection of patients for operation.

The measurement of stenosis of the internal carotid artery: comparison of doppler ultrasound, digital subtraction angiography and the 3D CT volume rendering technique.

OBJECTIVES: To determine the variability of measurement of stenosis of the internal carotid artery (ICA) using Doppler ultrasound, digital subtraction angiography (DSA) and the three-dimensional volume rendering technique (3D CT) in the high-grade stenosis band (70-100%). DESIGN: A prospective study of preoperative findings in 64 patients. MATERIAL AND METHODS: Doppler ICA stenosis was assessed according to combined Doppler acoustic standard criteria (CDASC) and peak systolic velocity (PSV). DSA and 3D CT stenosis were measured using the NASCET method. The results were compared using kappa statistics and Pearson's correlation coefficient. RESULTS: Agreement on the degree of ICA stenosis was statistically very good for DSA and 3D CT (kappa = 0.81, CI 0.69-0.93): Pearson's correlation coefficient was 0.88 (CI 0.76-0.90). The comparison of Doppler ultrasound with DSA showed good agreement (kappa 0.70, CI 0.58-0.82): Pearson's correlation coefficient was 0.61 (CI 0.43-0.74). The disagreement rate on occlusion was 3% between DSA and 3D CT and was rather high (10.9%) between Doppler ultrasound and DSA. CONCLUSIONS: The clinical decision to operate on an ICA stenosis will be strongly influenced by the diagnostic method used. DSA and 3D CT correlate well, whereas Doppler ultrasound tends to differ at the high end of the high-grade stenosis band (90% occlusion), underestimating (compared with DSA) the degree of stenosis.